Force Limiter

Abstract

To provide a cost-effective force limiter having a simplified structure in which the guide of a tension transmission element is simplified. [Solution] The present invention relates to a force limiter (1) for a seat belt of an automobile seat belt device, comprising an attachment portion (5), a deformable tube (2), a tension transmission element (3), and a displacement portion (4) connected to the tension transmission element (3) with tension resistance and arranged within or on the deformable tube (2), wherein the deformable tube (2) has a straight portion (21) within or at the open end (25) where the displacement portion (4) is held, and the deformable tube (2) has a deflection portion (22) formed integrally with the straight portion (21), and the tension transmission element (3) is deflected in the deflection portion (22).

Description

[Technical Field]

[0001] The invention relates to a force limiter having the features of the preamble of claim 1. [Background technology]

[0002] Seat belt systems are commonly used to restrain vehicle occupants in the event of an accident. To this end, seat belt systems include a seat belt that can be wound at a first end onto a belt reel of a belt retractor rotatably mounted on a frame that can be secured to the vehicle. To form a two-point belt, the seat belt can be provided with a belt tongue at its second end, which can be locked to a belt buckle fixed to the vehicle. To achieve a three-point belt, the seat belt can be fastened at its second end to an end attachment on the same side as the belt retractor of the vehicle seat, and the seat belt can be provided with a movable belt tongue, which can be locked to a belt buckle fastened on the other side of the vehicle seat to divide the seat belt into a three-point geometry.

[0003] The belt reel of the belt retractor is pre-tensioned in the retracting direction by a main spring supported on the frame, so that the seat belt is automatically retracted after the belt tongue is unlocked. Furthermore, a blocking device with an associated sensor device is provided to block the belt reel from further rotation in the seat belt extension direction when the belt webbing extension acceleration and / or vehicle deceleration exceed predetermined values. This means that when the belt reel is blocked, the occupant is restrained by the seat belt and is protected from collision with the internal vehicle structure.

[0004] Modern vehicles are also equipped with airbags, which may be positioned at various points on the vehicle structure and which inflate to cover the vehicle structure in the event of an accident. The combination of the seat belt system and the associated airbags restrains the occupants.

[0005] Since the occupant is further protected from a collision with the vehicle structure by the inflated airbag, it is advisable to provide the seat belt system with an additional force limiter, which allows a force-limited extension of the belt webbing in the event of a blocked belt reel. The force limiter can be assigned to the belt buckle, the end attachment, the deflector, the fastener of the belt retractor, or the belt reel.

[0006] Document DE 10 2017 101 807 A1 discloses a force limiter which is arranged on an end fitting or belt buckle and which comprises a straight deformation tube provided with a displacement part, which displacement part is connected to a tension transmission means in the form of a cable which in turn is connected to a belt transmission means in the form of a belt buckle or a cable loop, so that the seat belt is connected either directly to the displacement part or indirectly via the belt transmission means to the tension transmission means and via the tension transmission means to the displacement part.

[0007] If the tension applied to the displacement section exceeds the plastic deformation limit of the deformation tube, the displacement section is pulled through the deformation tube under the plastic deformation of the deformation tube, thus allowing force-limited extension of the seat belt even when the belt reel is blocked.

[0008] The deformation tube is formed by a straight tube fastened to a mounting fixture, through which the tension transmission means is further deflected. In addition to deflecting the tension transmission means, the mounting fixture also serves to fasten the force limiter to the vehicle structure. This means that the fastening point of the deformation tube to the mounting fixture is an interface through which the tension transmission means must pass. To ensure guidance of the tension transmission means in the area of ​​the interface, an additional connecting element is provided, through which the tension transmission means extends. The connecting element is supported on the mounting part and also serves to fasten the deformation tube to the mounting part. Summary of the Invention

[0009] Against this background, the object of the present invention is to provide a cost-effective force limiter having a simplified structure in which the guiding of the tension transmission elements is simplified.

[0010] According to the basic idea of ​​the invention, it is proposed that the deformable tube has a deflection section formed integrally with the straight section, in which the tension transmission element is deflected.

[0011] The advantage of the proposed solution is that the deformation tube is used in addition to deflecting the tension transmission element, so that the previously required deflection at the attachment point is no longer necessary. This also eliminates the need for an interface and the connecting elements required to bridge the interface and fasten the deformation tube to the attachment point. This, on the one hand, reduces the costs of manufacturing and assembling the force limiter, and, on the other hand, improves deflection by eliminating the need to deflect the tension transmission element through the interface.

[0012] It is further proposed that the deformation section comprises a deformation section, the deformation section having a non-circular cross section and an outer dimension that is larger than the inner diameter of the deformation tube in at least one direction of extension. Due to the non-circular cross section of the deformation section in the region of the deformation section, deformation of the deformation tube occurs in a preferred direction defined by the shape of the deformation section. The deformation tube is intentionally not uniformly expanded around its circumference, and zones are intentionally provided in the deformation tube that are deformed under higher loads with higher material stresses. This allows the use of cheaper materials or steels without compromising the ability of the deformation tube to undergo intentionally induced controlled deformation.

[0013] In this case, the non-circular deformation section can preferably have at least two cams protruding radially outward in its radially outer cross section. The deformation tube is thus intentionally widened in the area of ​​the cams. Furthermore, due to the corresponding shape of the deformation tube, the cams can be used to position the deformation section in a defined position relative to the deformation tube. The cams on the side of the deformation section facing the deflection or guide section can be designed with an inclined shape having a decreasing outer dimension, so that the deformation of the deformation tube is performed in an upward direction.

[0014] Furthermore, it is proposed that the non-circular deformation section has at least two flat sections in cross section, which intentionally create a free space between the deformation tube and the displacement section, allowing the deformation tube to be applied to or contracted by the displacement section during deformation.

[0015] It is further proposed that the cams and / or flat portions are arranged diametrically opposite each other at their opposite portions, so that the deformation tube is deliberately widened and deformed.

[0016] Furthermore, the cams and / or flat portions can be arranged equidistant from one another around the circumference of the displacement section, so that the deformation tube is deformed as uniformly as possible with as equal a plastic deformation range as possible around the circumference and in the area of ​​the cams.

[0017] It is further proposed that the displacement section has a cylindrical guide section having an outer diameter corresponding to the inner diameter of the deformation tube. The guide section serves to align the displacement section in the deformation tube at its mounting position and to guide the displacement section as it moves within the deformation tube. The guide section intentionally has an outer diameter corresponding to the inner diameter of the deformation tube, taking into account the tolerances to be applied, so that the displacement section does not cause any deformation of the deformation tube in the area of ​​the guide section. The guide section is arranged on the side of the deformation section facing the deflection section.

[0018] It is further proposed that the deformation tube comprises at least one radially inwardly molded bead in the region of the straight section, which bead limits the displacement path of the deflection part within the deformation tube, the bead limiting the displacement movement of the deflection part, which in effect forms a stop for the force-limited elongation of the belt webbing.

[0019] Furthermore, it is proposed that the mounting part comprises a fastening part for fastening the force limiter to a vehicle fixed structure, a first fastening part comprising the deforming tube in the region of the straight section, and a second fastening part comprising the deforming tube in the region of the deflection section. The design of the mounting part fixes the deforming tube in both the region of the straight section and the region of the deflection section. This fixes the deforming tube in the region of the straight section and absorbs forces acting on the deforming tube in this region during deformation. Furthermore, the deforming tube is additionally fixed in the region of the deflection section to absorb forces acting on the tension transmission element during deflection. Furthermore, the deforming tube is fixed in the region where the tension transmission element exits the deforming tube, which is advantageous for supplying the tension transmission element to the seat belt.

[0020] It is further proposed that the deformation tube is ovally shaped in the region of the open end of the deflection section. Due to the oval shape of the open end of the deflection section, the tension transmission element cannot move or can only move to a lesser extent in the preferred direction, but can be deliberately pivoted in the direction of the increased opening width within a larger pivot angle range. The force limiter can preferably be fastened to the vehicle in such a way that the tension transmission element can move less transversely to the seating surface of the associated vehicle seat and is therefore better aligned with the seating surface in the longitudinal or travel direction than in the longitudinal or travel direction.

[0021] Furthermore, it is proposed that at least one additional deformation or stop element is provided on the deformation tube in order to achieve a gradual or decreasing force limiting curve, which, by suitable arrangement and dimensioning, can achieve different force limiting curves, as long as this is advantageous for the restraint purpose, in particular for the purpose of further reducing the occupant load.

[0022] Furthermore, it is proposed that the position of the deformation or stopping elements can be changed by controllable actuators, which allows the force limiting curve to be actively modified and adapted, for example, to a detected accident scenario or a particular occupant.

[0023] It is further proposed that a blocking element is provided which blocks the displacement part and can be moved by a controllable actuator from a blocking position to a release position in which the displacement part is released, thereby allowing the activation of the force limiter to be actively blocked or deactivated.

[0024] Alternatively or additionally, it is proposed that a blocking element is provided which blocks the tension transmission element and which can be moved by a controllable actuator from a blocking position to a releasing position in which the tension transmission element is released. Activation of the force limiter can also be actively blocked or released by blocking or releasing the tension transmission element. [Brief explanation of the drawings]

[0025] The present invention will be described below using preferred embodiments with reference to the accompanying drawings. [Figure 1] 1 shows a force limiter according to the invention with a belt buckle in an unassembled state. [Figure 2] 1 shows a side view of a force limiter according to the invention with a belt buckle. [Figure 3] 1 shows the displacement part of the force limiter in different views. [Figure 4a] 4b shows a view of the displacement part and the force limiter in a cross-sectional view in the cross-sectional direction AA of FIG. 4a; [Figure 4b] 4b shows a view of the displacement part and the force limiter in a cross-sectional view in the cross-sectional direction AA of FIG. 4a; [Figure 5a] 10A and 10B show different cross-sectional views of a force limiter with a displacement portion in positions before and after force limiting. [Figure 5b]10A and 10B show different cross-sectional views of a force limiter with a displacement portion in positions before and after force limiting. [Figure 6a] 1 shows in cross section a force limiter with an additional actuator for influencing actuation and force limiting levels. [Figure 6b] 1 shows in cross section a force limiter with an additional actuator for influencing actuation and force limiting levels. [Figure 7] An alternative embodiment of the displacement part is shown in the different views. DETAILED DESCRIPTION OF THE INVENTION

[0026] FIG. 1 shows an exploded view of a force limiter 1 according to the present invention, showing its individual components before assembly. The force limiter 1 comprises a deformation tube 2, a tension transmission element 3, a displacement section 4, and an attachment section 5. One end of the tension transmission element 3 is connected to the displacement section 4 with a tension resistance, and the other end is connected to a belt buckle 7 with a tension resistance. Instead of the belt buckle 7, an end attachment, cable loop, deflector, or other component of the seat belt system can be provided, provided that, together with the tension transmission element 3, the linear movement of the displacement section 4 within the deformation tube 2, as described below, allows for force-limited elongation of the seat belt. The tension transmission element 3 is a rope, preferably a steel rope, which is inherently flexible and, due to its material properties and design, is able to absorb tensions arising during restraint without tearing or mechanically destroying itself.

[0027] The deformable tube 2 has a straight portion 21 and a curved deflection portion 22 formed integrally with the straight portion 21. The mounting portion 5 serves to fasten the force limiter 1 to the vehicle, and for this purpose has a plate-shaped fastening portion 53 with a fastening opening. The mounting portion 5 further has a first fixing portion 51 and a second fixing portion 52, each of which is annular or clamp-shaped and serves to hold the deformable tube 2 on the mounting portion 5, i.e., to fix and hold the deformable tube 2 to the vehicle.

[0028] The mounting part 5 comprises the deforming tube 2 with an annular first fixing part 51 in the region of the end of the straight part 21 facing the deflecting part 22. The first fixing part 51 is intentionally dimensioned somewhat longer and more tubular in shape so that the deforming tube 2 finds a stable support within the first fixing part 51. A second fixing part 52 of the mounting part 5 comprises the deforming tube 2 in the region of the deflecting part 22 and thus further fixes the deflecting part 22 relative to the straight part 21. The deforming tube 2 is thus virtually fixed in its geometric shape by the two fixing parts 51 and 52.

[0029] The straight section 21 of the deformation tube 2 has an open end 25, as can be seen in FIG. 4b, in which or on which the deflection section 4 is arranged. The tension transmission element 3 is connected with a tension resistance to the deflection section 4 and extends from the deflection section 4 through the straight section 21 of the deformation tube 2, deflecting in a predetermined direction at a deflection section 22 of the deformation tube 2 formed integrally with the straight section 21. The deformation tube 2 has an elliptical shape in the region of the open end 24 of the deflection section 22, so that the tension transmission element 3 can perform a larger movement, in particular a pivotal movement, in a preferred direction than in a direction perpendicular thereto. The preferred direction may correspond to the direction of travel and / or the longitudinal direction of the seating surface of the associated vehicle seat, so that the belt buckle 7 or end attachment held on the tension transmission element 3 can perform a deliberately larger movement in the direction of travel or the longitudinal direction of the seating surface, with limited movement transverse to this direction.

[0030] The displacement section 4 has a cylindrical guide section 41 with a circular cross section and a deformation section 42 with a noncircular cross section. The displacement section 4 further has a through-opening 426 through which the tension transmission element 3 extends. The tension transmission element 3 is pressed, glued, or tension-resistantly connected to the displacement section 4 in the through-opening by a thickened protruding end. The guide section 41 has an outer diameter B that is identical to the inner diameter D of the straight section 21 of the deformation tube 2, taking into account dimensional deficiencies, so that the displacement section 2 with the guide section 41 can be inserted into the open end 25 and lie as flat as possible against the inner wall of the straight section 21. The deformation section 42 has a noncircular cross section and includes two cams 421 and 422 arranged diametrically opposite each other on the radial outside and equidistant from each other in the circumferential direction, and two flat sections 423 and 424 arranged diametrically opposite each other and equidistant from each other in the circumferential direction. The cams 421 and 422 cause the deforming portion 42 to have an outer dimension A that is larger than the inner diameter D of the straight portion 21 of the deforming tube 2. The cams 421 and 422 are formed on their edge sides facing the edge of the deforming tube 2 in an inclined shape that starts from the guide portion 41 and becomes higher as it goes outward.

[0031] Furthermore, on the side of the straight section 21 facing the deflection section 22, the deformation tube 2 has, diametrically opposed, at least two radially inwardly projecting beads 23 or one circumferential bead 23, which are dimensioned such that a gap is formed between their radially inner end faces, through which the tension transmission element 3 extends. The gap formed by the beads 23 serves to guide the tension transmission element 3 and to form a stop for limiting the movement of the deflection section 4, which will be explained in more detail below, during force-limited elongation of the belt webbing.

[0032] Furthermore, an additional conically tapering deformation element 6 in the form of a plastically deformable material is provided, which extends from the bead 23 in the direction of the open end 25 of the straight section 21 of the deformation tube 2 .

[0033] In Figure 4b, the force limiter 1 can be seen before activation in the cross-sectional direction AA of Figure 4a. The deflection part 4 together with the guide part 41 is positioned so as to protrude into the straight part 21 of the deflection tube 2, while the deflection part 42 is located outside the deflection tube 2, i.e., outside the open end 25 of the straight part 21 in the right-hand view of Figure 4b.

[0034] In this position of the force limiter 1, if a tension greater than the plastic deformation limit of the deformation tube 2 in the area of ​​the straight section 21 is applied to the tension transmission element 3 via the seat belt, the displacement section 4 is pulled from its initial position to position 4' shown in Figure 5a. The deformation tube 2 is expanded in the area of ​​the straight section 21 by the cams 421 and 422, thereby undergoing plastic deformation. At the same time, the deformation tube 2 is pulled laterally in this area toward the flat sections 423 and 424, as can be seen in cross-section DD in Figure 5b. This causes the deformation tube 2 to plastically deform into a geometric shape corresponding to the cross-sectional shape of the deformation section 42. The deformation section 42 contributes to the plastic deformation of the deformation tube 2 in the area of ​​the straight section 21; it is not excluded that the deformation section 42 itself may also deform slightly. The deformation of the straight section 21 by the cams 421 and 422 occurs outward in two preferred directions, simultaneously abutting laterally against the flat sections 423 and 424. The plastic deformation of the deformation tube 2 is the basis for the energy absorption that is the basis for the force-limited elongation of the tension transmission element.

[0035] The proposed shape of the displacement part 4 results in a defined stress state during movement of the displacement part 4 and a force-limited elongation of the belt webbing within the deformation tube 2 during plastic deformation, which allows for an improved defined deformation of the deformation tube 2 and achieves defined force limiting levels even when using cheaper steels or material types, thereby further reducing the manufacturing costs of the force limiter 1.

[0036] When a bead 23 and an additional deformation element 6 are provided, as in this embodiment, the force-limited extension of the tension transmission element 3 can be designed to be limited at first and gradually increase towards its rear end.

[0037] In figure 6b the force limiter 1 can be seen in a further developed embodiment according to the cross-sectional direction AA of figure 6a.

[0038] In order to control the force limiter 1 and its force limiting curve, various control devices 8, 9 and 10 are provided on the force limiter 1. Thus, a control device 8 is provided which has a blocking element 81 which abuts the displacement member 4 in a blocking position to block its movement. The control device 8 further comprises an actuator 82 which, when activated, moves the blocking element 81 from the blocking position to a release position, so that the displacement member 4 is released to perform the aforementioned movement.

[0039] Furthermore, a control device 9 is provided, which has a stop element 91 protruding into the path of movement of the displacement section 4 and a controllable actuator 92 which, when activated, moves the stop element 91. The stop element 91 can limit the path of movement of the displacement section 4 and thus the extension length of the force-limited belt. Alternatively, the stop element 91 can be used as an additional deformation element, following the example of the conical deformation element 6, which is intentionally plastically deformed when passing through the displacement section 4, thus increasing the level of force limitation. This makes it possible to achieve different force limitation curves depending on the position of the stop element 91 or deformation element.

[0040] Furthermore, a control device 10 is provided, which has a blocking element 11 that in a blocking position abuts the belt buckle 7 or clamps the end of the tension transmission element 3. The control device 10 further comprises an actuator 12 that, when actuated, moves the blocking element 11 from the blocking position to a release position, in which the belt buckle 7 or the tension transmission element 3 is released.

[0041] The control devices 8, 9, 10 can be provided individually or in any combination in the force limiter 1. The actuators 12, 92, and 82 can be designed as electrically controllable drives or as pyrotechnic drives with electrical ignition. In either case, the control devices 8, 9, 10 allow the force limiter 1 to have an accident-specific and / or occupant-specific force limiting curve.

[0042] 7 shows an alternative embodiment of the displacement unit 4 having three cams 421, 422, and 425 arranged in a star shape and equally spaced around the circumference. The three cams 421, 422, and 425 are arranged so that their centers form an angle of 120 degrees with respect to each other. The cams 421, 422, and 425 are formed in a manner that, in the portions facing the guide portion, they are inclined toward the guide portion 41, so that the cams 421, 422, and 425 deform the deformation tube 2 while increasing the plastic deformation during the force-limited movement.

Claims

1. A force limiter (1) for a seat belt system of a motor vehicle, comprising: - a mounting part (5), - a deformed tube (2), - a tension transmission element (3), a deflection part (4) connected with tension resistance to said tension transmission element (3) and arranged in or on said deformation tube (2); Equipped with - the deformable tube (2) has a straight section (21) in or at the open end (25) where the displacement section (4) is held; A force limiter, the deformable tube (2) has a deflection section (22) integrally formed with the straight section (21), in which the tension transmission element (3) is deflected; Force limiter (1).

2. A force limiter (1) according to claim 1, wherein the displacement portion (4) comprises a deformation portion (42) having a non-circular cross section, the cross section of which in at least one direction of extension has an outer dimension (A) that is greater than the inner diameter (D) of the deformation tube (2).

3. A force limiter (1) according to claim 2, wherein the non-circular deformation portion (42) comprises, in cross section, at its radially outer side at least two radially outwardly projecting cams (421, 422, 425).

4. A force limiter (1) according to claim 2 or 3, wherein the non-circular deformation portion (42) has at its radially outer side at least two flat portions (423, 424) in cross section.

5. A force limiter (1) according to claim 3 or 4, wherein said cams (421, 422, 425) and / or said flat portions (423, 424) are arranged diametrically opposite each other.

6. A force limiter (1) according to any one of claims 3 to 5, wherein the cams (421, 422, 425) and / or the flat portions (423, 424) are arranged equidistant from one another around the circumference of the displacement part (4).

7. A force limiter (1) according to any one of claims 1 to 6, wherein the displacement part (4) has a cylindrical guide part (41) with an outer diameter (B) corresponding to the inner diameter (D) of the deformation tube.

8. A force limiter (1) according to any one of claims 1 to 7, wherein the deforming tube (2) is provided in the region of the straight portion (21) with at least one radially inwardly shaped bead (23), which bead (23) limits the displacement path of the displacement portion (4) within the deforming tube (2).

9. A force limiter (1) according to any one of claims 1 to 8, wherein the mounting part (5) comprises a fastening portion (53) for fastening the force limiter (1) to a vehicle fixed structure, a first fixing portion (51) comprising the deforming tube (2) in the region of the straight portion (21), and a second fixing portion (52) comprising the deforming tube (2) in the region of the deflection portion (22).

10. A force limiter (1) according to any one of the preceding claims, wherein the deforming tube (2) is elliptical in the region of the open end (24) of the deflecting portion (22).

11. A force limiter (1) according to any one of claims 1 to 10, wherein at least one additional deformation element (6) or stop element (91) is provided in the deformation tube (2) to achieve a gradual increasing or decreasing force limiting curve.

12. A force limiter (1) according to claim 11, wherein the position of the deformation element (6) or the stop element (91) is variable by a controllable actuator (92).

13. A force limiter (1) according to any one of claims 1 to 12, comprising a blocking element (81) for blocking the displacement part (4), the blocking element (81) being movable by a controllable actuator (82) from a blocking position to a releasing position for releasing the displacement part (4).

14. A force limiter (1) according to any one of claims 1 to 13, comprising a blocking element (11) for blocking the tension transmission element (3), the blocking element (11) being movable by a controllable actuator (12) from a blocking position to a releasing position for releasing the tension transmission element (3).

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